During drilling operations, sensors are often utilized to measure various forces exerted on a drill string. Exemplary forces include weight-on-bit (WOB), toque-on-bit (TOB) and bending loads/forces on various parts of the drill string. These forces can affect the dynamic behavior of the drill string, and if not monitored, can result in damage to downhole components or compromised operation. Such measurements provide information that can be used to, for example, measure drilling parameters or monitor downhole conditions.
Commonly WOB, TOB and bending loads on a drill strings are measured by strain gauges. The most common type of strain gauge consists of an insulating flexible backing which supports a metallic foil pattern. As the object is deformed, the foil is deformed, causing its electrical resistance to change. This resistance change, usually measured using a Wheatstone bridge, is related to the strain by the quantity known as the gauge factor.